The acid-pepsin secretion and contractile activity of the mammalian stomach in response to electrical stimulation of the vagus nerves has been examined in vivo and under in vitro perfused conditions. Vagal stimulation causes both phasic contractions of the pyloric antrum and sustained contractions of the cardia. At high intensity stimulation the base-line level between stimulations fell, particularly in the cardia. The threshold for stimulation of contractions is lower than that for secretion. The properties of the nerves are consistent with C fibers for both motor and secretory effects. Gastrin plays only a permissive role. It is unlikely that effects on secretion can be obtained independently of those on secretion. Reflux vagal stimulation of the stomach is difficult to demonstrate because of central inhibitory effects.